This is so odd , reminds me of South Park and the nurse. A girl had her twin sister inside her and it was discovered when she got sick. The story is from AP services and referenced here and a quote from the short article here.

ATHENS, Greece (AP) -- A 9-year-old girl who went to hospital in central Greece suffering from stomach pains was found to be carrying her embryonic twin, doctors said Thursday.

In essence this young girl had her own clone growing inside her. And it happened naturally.

And in this general vein of weird science there is a robot birth simulator. Essentially a robot that simulates birth.I am not sure what will happen when I see a headline that a robot gives birth to first human.

Nature is just odd, there are some insects that clone themselves for months at a time until their numbers are huge.